1. Field of the Invention
This invention relates to a brake control apparatus for a vehicle.
2. Description of the Prior Art
For example, U.S. Pat. No. 4,247,154 discloses the brake control apparatus in which the valve apparatus interconnected to a clutch pedal is closed by treading the clutch pedal and so the brake fluid pressure is held in the wheel cylinder of the automobile on the upwardly inclined roadway. Thus, the driver can release the foot from the brake pedal, while the automobile can be maintained to stop on the upwardly inclined roadway. However, the clutch pedal should continue to be trodden for holding the brake fluid pressure.
To start the automobile, the driver or operator shifts the gears and gradually releases the clutch pedal from treading. The clutch mechanism connected to the clutch pedal through the wire is put into the semi-clutching condition. In such a condition, the driver steps on the accelerator pedal to raise the speed of the engine. Thus, the automobile starts to run.
As above described, when the automobile should be brought to a stop facing upwardly on an inclined roadway, the clutch pedal is trodden to close the valve apparatus. And when the automobile is started to run, the clutch pedal is released to open the valve apparatus. However, when parts related to the valve apparatus or clutch pedal such as a clutch friction lining wear, the relationship changes between the pushed position of the clutch pedal and the timing of transmitting the drive force sufficient to start the automobile from the engine to the wheel through the clutch friction lining, although the relationship is constant between the pushed position of the clutch pedal and the timing of opening the valve apparatus. Thus, before the drive force sufficient to start the automobile is transmitted to the wheel, the braking force is relieved.
In the prior art, when the position of the clutch pedal puts the clutch apparatus into the semi-clutch condition, the braking force is set to be relieved. However, when the clutch friction lining wears, the position of the clutch pedal for putting into the semi-clutch condition changes. The timing of relieving the braking force is not changed with the position of the clutch pedal for putting into the semi-clutch condition. That is the reason for the above-described disadvantage.
When the timing of transmitting the sufficient drive force to the wheel does not correspond with the timing of relieving the braking force, there is the danger that the automobile is moved backwards to cause an accident on the start on the upwardly inclined roadway.
In order to solve the above described problems, the same assignee as this application proposed in the U.S. application No. 797,941, filed Nov. 14, 1985, the brake control apparatus of the drum brake type which can effect a proper operation in accordance with the condition of the wheel or body on the start and stop of the automobile.